% clear all;
a1 = [2.1,0.8,2.3,3.5]';
a2 = [3.4,-0.3,7.9,7.2]';
a3 = [-1.2,4.1,-1.5,1.7]';
a4 = [2.3,2.8,1.4,-9]';
A = [a1,a2,a3,a4];
x = [1,2,3,4]';

[P,D] = eig(A);
P
D